"Meanwhile in Gotham..."
1. Game start with Gordon saying
"Joker gang, are acting weird/unusual, you must investigate"

2. after beat somes of gangs you face catwoman boss, aftr beat her, selina say:
"i have not ideia what is happening, but a little bird told me, joker and harley are planing a assault to central bank"

3. them start the car shoter stage, with harleyqueen-car boss, and after that you go to 2 levels until face joker at a building rooftop, after beat him, joker say:
"I looks like someone which made plans? luthor just gave me money to hire more guys and have fun, hahahahahaha"

4. stage start at metropolis buildigns, to fight against luthor, after bet him,
"is to late, all pieces are on place, justice league end are close"

5. alarm call heroes atention to streets where army will be there fighting against heroes, after beat soldiers and zoom,
Lois Lane come and say "Luthor discoverd where Doomsday are locked, on a secret militar base, go, you must stop it"

6. the water-sky level, fight agains metallo, later that part to be secret base entrance (check wonder woman video) to fight against General Wade

7. inside of base you will fight until beat parasite.

8. but Cyborg Superman will come and release Doomsday and fly away.... im not sure if he must talk something here....

9.then some hero, probably batman or super, say:
"They want to back to cities to spread destruction, we must stop them before Doomsday recover all his strong"

10. one level at rooftoops where you fight against supercyborg

11. final fight against doomsday on a build consctruction area

12. End - Game end with death of superman, i tink dont need any text, just some cool pics.
.....
and last cutscene should be Darkseid saying something like "Earth are defenseless...."